Dividing Decimals/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim and Moby are in a van labeled: Divide and Conquer, Winter Tour. Moby is driving, and Tim is sitting in the front passenger's seat. It is night. They pull into a gas station. The van's door slides open and little DJ robots jump out. One of them, Deadmau5 walks to the driver’s side window. DEADMAU5 ROBOT: Blip. TIM: Um, sour cream and onion. The three little robots walk into the convenience store. Moby and Tim wait in the van. MOBY: Beep. TIM: Yeah, road trips rock. Blazing a new path, the wind in your hair, daily grind in the rearview. MOBY: Beep. Moby interrupts Tim and hands him a sheet of paper. TIM: Nice. Fan mail. He looks at the letter and his expression droops. TIM: Oh. Tim reads from the typed letter. TIM: Dear Tim and Moby, dividing decimals is confusing. Am I going to have to do this in real life? Thanks, Tamia. Tim and Moby are waiting outside the van when the little DJ robots return with chips, cookies, and other snack foods. ROBOTS: Blip, bloorp. TIM: Dividing decimals can actually come in handy, Tamia. Especially when you're divvying up stuff or working with money. Like figuring out how much we each owe for this, uh, lunch. MOBY: Beep. TIM: Let's see, the total cost is $29.35. Tim takes the receipt from the little Deadmau5 robot and looks at it. TIM: And there are one, two, three, four, five of us. We can write out the numbers like a regular division problem. One of the little robots uses a laser to write the equations on the side of the van. He writes "29.35 divided by 5" as a fraction, a long division equation, and a division sign equation. TIM: There's one decimal point in the dividend, the number we're dividing. For now, we can just forget about it and solve the long division like normal. The dividend, 29.36, illuminates. The robot erases the decimal point, leaving the long-division equation 2,935 divided by 5. MOBY: Beep. TIM: Okay, 5 goes into 29 five times, with 4 left over. The 3 from the dividend travels down to the remainder. TIM: 43 divided by 5… 8 is added to the quotient, with 3 left as the remainder. The 5 from the dividend travels down to the remainder. TIM: …And 5 into 35. Tim uses the laser to solve the problem as he states his steps aloud. The final answer for 2,935 divided by 5 is 587. Tim places a dollar sign in front of the solution. Moby opens up his wallet, and a moth flies from it. Moby looks concerned. MOBY: Beep. TIM: Don't worry. There's no way we each owe $587 Moby smiles. TIM: Remember, we're splitting 29.35 five ways. So, the quotient has to be way smaller than 29. A pie chart labeled $29.35 appears and splits into five equal slices. MOBY: Beep. TIM: We have to put our decimal back in the dividend. One little robot uses the laser to return the decimal to the 2,935. It now reads: 29.35. TIM: Then slide a decimal up into that same spot in our quotient. A decimal is inserted into the number 587, making it 5.87. TIM: It's a simple trick, but it works. MOBY: Beep. TIM: Well, let's make an estimate just to be sure. First, we'll round that dividend to the nearest whole number, 29. About how many times does 5 go into 29? The little robot uses his laser to change 29.35 to 29. The equation changes to 29 divided by 5 equals question mark. TIM: Or, put another way, 5 times what equals 29? MOBY: Beep. TIM: Well, we all know that 5 times 6 is 30 and 5 times 5 equals 25. The little robot uses his laser to write Tim's equations on the side of the van. TIM: So the answer to our division problem should be between 5 and 6, but closer to 6. MOBY: Beep. TIM: Yep, it's confirmed. Pony up, guys: $5.87 each. The little robot with the laser uses it to circle the figure $5.87 on the side of the van. MOBY: Beep. Moby is holding a large jar labeled: Gas Money. Tim is eating chips from a bag. TIM: Um, I think this is more than enough to keep us going. Tim points to the bag of chips. Then he realizes that Moby is talking about money for gas. TIM: Oh, right. That kind of fuel. A hybrid this baby is not. Tim pats the side of the van. TIM: We've saved up $52.03, and gas will run us $2.42 a gallon. The label on the money jar now reads: $52.03. The little robot with the laser burns the long-division equation 52.03 divided by 2.42 into the side of the van. TIM: Now our divisor has a decimal, too. That means one extra step in our problem solving. MOBY: Beep. TIM: We have to move the decimal over until it's a whole number. One, two. The robot uses the laser to change 2.42 to 242. TIM: Which means we have to do the same thing to the dividend. Slide it over two places, then back to some long division. The robot uses the laser to change 52.03 to 5203. MOBY: Beep. Side by side images compare the equation 52.03 divided by 2.42 with the equation 5203 divided by 242. TIM: It does seem like we changed the equation. But let's look at what really happened. Every decimal jump to the right is really multiplying the number by 10. So, that's 10 times 10 on the dividend and 10 times 10 on the divisor. A small robot uses digital numbers to illustrate Tim's explanation. Dividend 52.03 is multiplied by 10 times 10 and becomes 5203. Divisor 2.42 is multiplied by 10 times 10 and becomes 242. TIM: In other words, we multiplied our problem by 100 over 100. MOBY: Beep. TIM: Right. Otherwise known as 1. An image shows the fraction 100/100. That fraction changes to 1. TIM: And as we know, multiplying by 1 doesn't change a number's value. So our quotient will be the same. Text reads: 52.03 divided by 2.42 equals 5203 divided by 242. MOBY: Beep. TIM: Now, all we have to do is some regular long division. Tim talks through the steps of solving the equation 5203 divided by 242. TIM: Let's see, 242 into 520. I know 250 times 2 is 500, so let's try 2. The 242 on the van is multiplied by 2 to equal 484. 484 is subtracted from 520 to equal 36. TIM:36 left over. So now we have 242 into 363. The 3 from the dividend travels down to make the remainder 363. TIM: We already know that 242 times 2 is 484. So, it must go into 363 once. The equation on the van shows the incomplete quotient to be 21. MOBY: Beep. TIM: Yep, we still have a remainder. Whatever 363 minus 242 is. So,121. The completed equation reads: 5203 divided by 242 equals 21 with a remainder of 121. TIM: But since this is a decimal problem, we don't just leave it at that. We need to add a decimal and a trailing zero. And we'll put the decimal in the same spot in our quotient. A decimal point and a zero are added after the 5203. The trailing zero drops down, changing the remaining 121 into 1210. A decimal point is added after 21 in the quotient. TIM: So now it's 242 into 1,210. I know that 250 goes into 1,000 four times, and this is 210 more than that. Let's try a 5. Tim mumbles as he checks out his figures. He multiplies 242 by 5. The quotient 21.5 is highlighted as Tim says it. TIM: 1,210. So, there you have it. We've got enough gas for 21.5 gallons. Now, enough of this math. Let's hit the road and get ready to... MOBY: Beep. Tim pauses. Moby points to the gas pump. He has pumped 32 gallons of gas into the van, and they owe $77.44. Tim finishes his sentence. TIM: …rock. Tim frowns at Moby. TIM: Well, another fine mess you've gotten us into. Crickets chirp as they realize they are stranded. Category:BrainPOP Transcripts Category:BrainPOP Math Transcripts